Case IH 520560-03 - BCM – BCM: Cab left wiper motor - short circuit to B+

The control module has detected that the electrical circuit for the cab's left-hand windshield wiper motor is shorted to a battery voltage source (B+). This means the circuit is receiving 12V power when it shouldn't be. This condition typically causes the wiper motor to run continuously without being switched on, fail to park correctly, or blow the associated circuit fuse to protect the system.

• MAGNUM AFS Connect
• Steiger AFS Connect

1. 1

   Inspect the cab fuse panel for blown fuses related to the wiper system, as a short to B+ can backfeed and blow accessory fuses.

2. 2

   Visually inspect the wiring harness running from the BCM to the left wiper motor for pinched wires, chafed insulation, or melted loom where the power wire might touch a constant 12V wire.

3. 3

   Disconnect the electrical connector at the left wiper motor, turn the key ON with the wiper switch OFF, and check for 12V at the motor connector's power pin to isolate a harness or BCM short.

4. 4

   Ensure the multifunction wiper switch in the cab is not internally shorted and sending a constant 'ON' signal to the BCM.

5. 5

   Check the pins on the wiper motor itself for continuity to ground to test for an internal motor failure.

1. 1

   Disconnect Power

   Turn off the machine and disconnect the negative battery cable to prevent electrical spikes during repair.

2. 2

   Repair Wiring

   If the diagnostic checks revealed a chafed or pinched wire in the roof harness or A-pillar harness, cut out the damaged section. Splice in a new section of wire of the same gauge, solder the connection, and seal it with marine-grade heat shrink.

3. 3

   Replace the Wiper Motor

   If the motor itself is internally shorted, remove the wiper arm from the exterior spline. Remove the interior cab trim covering the left wiper motor. Unbolt the motor bracket, disconnect the harness, and install the new motor.

4. 4

   Replace the BCM

   If the harness and motor are perfectly fine but the BCM is constantly outputting 12V to the circuit (a stuck internal driver/relay), the BCM must be replaced. Note: BCM replacement requires a Case IH dealer EST (Electronic Service Tool) to program the new module to the tractor.

5. 5

   Reassembly and Testing

   Reconnect the battery. Clear the inactive 520560-03 fault code via the AFS Pro display or diagnostic tool. Turn on the wipers to verify all speeds and the 'park' function operate correctly.